Add the cranberries, apples and orange rind to a preserving pan, orange shells and any pips tied in muslin. Make the orange juice up to 300 ml (½ pint) with water then add to the preserving pan. Cover and simmer gently for 30 minutes, stirring from time to time, until the fruit is tender.
Pour the sugar into the pan and heat gently, stirring from time to time, until dissolved. Bring to the boil, then boil rapidly until setting point is reached (10–15 minutes). Squeeze the muslin bag between two wooden spoons to extract as much juice as possible, then discard. Skim with a draining spoon or stir in the butter, if needed.
Ladle into warm, dry jars, filling to the very top. Cover with screw-top lids, or with waxed discs and cellophane tops secured in place with elastic bands. Label and leave to cool.
To serve, try spreading the jam liberally on buttered, toasted bagels.